"""Schema 4: split animated symbol palettes from the authoring palette.

Before schema 4 a symbol's ``:palette`` leaf value was always a channel. It now
names the static palette used when that symbol is the viewed root, while the
old channel is retained as ``:palette-channel`` compatibility data. New edits
use a real lane symbol referenced by ``:palette-track``.
"""

from django.db import migrations, models


def forwards(apps, schema_editor):
    Leaf = apps.get_model("clips", "Leaf")
    Project = apps.get_model("clips", "Project")
    for leaf in Leaf.objects.filter(path__contains="/symbol/"):
        parts = leaf.path.split("/")
        if len(parts) != 4 or parts[2] != "symbol":
            continue
        value = leaf.value
        if not (isinstance(value, list) and value[:1] == ["^ "]):
            continue
        out = list(value)
        changed = False
        for i in range(1, len(out) - 1, 2):
            if out[i] == "~:palette" and isinstance(out[i + 1], list):
                out[i] = "~:palette-channel"
                changed = True
        if changed:
            leaf.value = out
            leaf.version += 1
            leaf.save(update_fields=["value", "version"])
    Project.objects.update(schema_version=4)


class Migration(migrations.Migration):
    dependencies = [("clips", "0012_sound_label")]

    operations = [
        migrations.AlterField(
            model_name="project",
            name="schema_version",
            field=models.PositiveIntegerField(default=4),
        ),
        migrations.RunPython(forwards, migrations.RunPython.noop),
    ]